<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>无标题文档</title>
<style>
.box{height:2000px;}
.div{width:100px;height:100px;background:red; position:fixed;left:100px;top:100px;_position:absolute;_top:expression(eval(document.documentElement.scrollTop+100));
}
</style>
</head>
<body>
<div class="box">
	<div class="div"></div>
</div>
</body>
</html>
